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ties of the

III. Intrin- other so closely, that they may be considered as modifisic proper

cations of one and the same substance. Each of these blood. three substances yields, when decomposed, but does not and car- contain, earthy phosphates and carbonate of lime; for bonate of

the entire blood holds in solution no earthy phosphate, far existent except, perhaps, in too small a quantity to be detected. in the blood.

From these earths it is clear that the bones derive their How the bones are earthy supply; which, however, it is also clear they can supplied

only do, as in the case of the formation of gelatine, in with earthy materials. consequence of a decomposition of the blood as it arrives

at the secernents of the bones. Colouring Vauquelin endeavoured to separate the colouring matmatter, how separatable.

ter from the blood by means of sulphuric acid : but this material is not wanted, and does not very well answer the purpose. A method proposed by M. Berzelius in another communication is much simpler as well as more effective*. It consists in placing the clot or coagulum of blood upon blotting paper, to get rid of the serum as completely as possible. The clot is then to be put into water, in which the colouring matter dissolves, while the fibrin remains unaffected; when the water being evaporated, the colouring matter is obtained in a separate state. On reducing this matter to ashes, about zóó of

iron can always be separated. Whence It is difficult to determine by what means the iron or phur, &c.

the sulphur, or the elementary principles of calcareous obtain an earth, obtain an existence, or the means of existence, existence in

in the blood. If these materials were equally diffused throughout the surface of the earth, we might easily conceive that they are introduced through the medium of food. But as this is not the case; as some regions, like New South Wales, at least on this side the Blue Mountains, contain no lime-stone whatever, and others no iron or sulphur, while all these are capable of being obtained apparently as freely from the blood of the inhabitants of such regions, as from that of those who live in quarters where such materials enter largely into

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the blood.

. Ann. de Chim. et de Phys. v. 42.

exists

n any other

the natural products of the soil; it is perhaps most rea- III. Intrinsonable to conclude that they are generated in the labo- ties of the ratory of the animal system itself, by the all-controlling blood. influence of the living principle. . What may be the aggregate quantity of any of these Aggregate

amount of minerals in the mass of blood belonging to an adult, has iron in the not been determined with accuracy. The amount of blood of an

adult. the iron has been calculated by Parmentier and Deyeux, upon grounds furnished them by Menghini, at seventy scruples, or very nearly three ounces, estimating the average of blood in the vessels of an adult at twenty-four pounds, which is most probably something short of the mark.

Whether iron exists in any other part of the animal Whether frame than the colouring matter of the blood, is in some degree doubtful. Vauquelin seems to have traced it in part than egg-shells and oyster-shells; and Mr. Brande thinks he

the colour

ing matter. has done the same in the chyle and in the serum, and this as largely as in the colouring matter of the blood, which, after all, he thinks contains only a very minute quantity*. But these experiments are too indefinite, and by no means coincide with those of Berzelius, since confirmed by other chemists. If the experiments of Menghini may be relied upon, human blood contains a larger proportion of iron than that of quadrupeds ; quadrupeds have more than fishes; and fishes more than birds. But though there can be no longer any question of W

the iron is the existence of iron as a constituent principle in the intended to blood, we are in total ignorance of the part it is intended perform. to perform. It is, perhaps, the colouring material, though, as I have already observed in the physiological proem to the preceding class, even here we are still very much in the dark, and are overwhelmed with contending hypotheses. It is probable that the red particles of the blood contribute to the strength of animals to whom they are natural, as conjectured by Mr. J. Hunter, and that the strength of such animals is in proportion, or nearly,

. Phil. Trans. 1812, p. 112.

VOL. II.

ties of the blood,

particles of the blood,

III. Intrin. so, to their number. Yet such particles are never found sic proper in the blood of several classes of animals, as insects and

worms: and in those in which they are found, they have often no existence in the commencement of life; for they are not discoverable in the egg of the chick, when the heart first begins to pulsate; nor are they, in any animals, pushed into the extreme arteries, where we must suppose the serum reaches. And hence, whatever their value, they cannot be regarded as the most important part of the blood, or as chiefly contributing to the growth

and repair of the system*. Form and Various attempts have at different times been made, diameter of the red to determine the form and measure the diameter of the

corpuscles of the blood, but even this does not seem to have been accompanied with very great success. Della Torre, by applying his microscope, detected them, as

he thought, to be flat circles or rings with a perforation Hewson's in the centre; and Mr. Hewson ascribed to them the hypothesis:

same shape, but represented them as hollow or vesicular, with a dot of red colouring matter in the centre instead of a perforation; so that, if his description could have been substantiated, they might literally have been regarded as the wheels of life moving on iron axles. Mr. Hewson's hypothesis, however, extended much farther; for, by a variety of plausible experiments, he persuaded himself, and many others also, that it is the office of the thymus and lymphatic glands to secrete and elaborate these vesicles which are then carried by the lymphatics and thoracic duct to the arteries, and from the arteries

to the spleen which furnishes them with their coloured long since axles. Some of these physiological and microscopic di

vertisements however, have been long overturned; while the general shape of the corpuscles has been gravely shown by other exquisite analyses to be globular; the

diameter of which, as measured by the microscopical Bauer's experiments of M. Bauer, is gooo part of an inch; a microscopic dimension, however, which has since been reduced by experi

overthrown.

ments.

* On Blood, pp. 46. 48.

per

Captain Kater to sobo part of an inch*. M. Bauer has III. Intrin: also ascertained, as he thinks, that it is not the centre of sic

ties of the the globule that is dotted, but its outline that is sur- blood. rounded with colouring matter; so that, instead of being annular wheels with iron axles, they are spherular wheels with iron tiers. It is somewhat singular that, in the revolution of science, M. Bauer's views are now sinking below the horizon, while those of Mr. Hewson are again ascending into notice: for the later experiments of M. Prevost, have restored to the red corpuscles of the blood their flat circles and points: and divested them of a globular form. MM. Prevost and Dumas, believe the co- Experi

ments of louring matter to be a membrane by which these cor- Duma puscles are surrounded. They pursued a dextrous method of drying the red particles as soon as separated, and found that when divested of this red matter and rendered colourless, they are of the same size in every animal they examined; being 1.7600 part of an inch. But that, with the colouring matter, the size differs in different animals; being 1.3100 of an inch in man, the dog, rabbit, pig, guinea-pig and hedge-hog; in the ass 1.4200; the cat and man, 1.4300 : the sheep, horse, mule, and cow 1.500; and the goat 1.700. These particles have a peculiar tendency to form themselves into lines, as observed by Sir E. Home; the lines resembling in every respect the muscular fibre. Fibrin they found also to be a collection of colourless corpuscles of the same kind as the above; the same corpuscles may be also traced in the white of the egg. Those of a chick six days after incubation, they found larger than those of a hen; as also that those which in some young animals are circular afterwards become ellipticalt. Even this last was also observed by Hewson: and the remarks may lead to some facts connected with inflammation by which they may be influenced; as they may be likewise by the temperature of hot climates. ..ver We have also still much to learn, not merely in re- Real differ

Loutrone Prevost.

ence be

tween the + Phil. Trans. 1818, pp. 173. 187. Annales de Chimie, in Loco. blood of

different

III. Intrine spect to the real difference between human blood and that ties of the

of quadrupeds, but the real difference between that of blood. any one species of animal and any other. M. Berzelius

observes that “the great agreement in the composition species undetected.

of human and ox blood is remarkable, and explains to us the possibility of the phænomena observed in the experiments in transfusion.” But we have a clear proof that the blood of one species of animals differs so much from that of another, either in its principles or their modification, that no benefit can result from transfusion, unless from like kinds to like kinds. Thus, according to several interesting experiments of Dr. Blundell, a dog, asphyxiated by hemorrhage, may easily be recovered by a transfusion of blood from another dog, but is little or not at all relieved if the blood be taken from man*; and the experiments of MM. Prevost and Du

mas precisely coincide with this doctrine. Blood, in Upon the whole, however, we cannot but regard the many respects, the

blood as in many respects the most important fluid of most im- the animal machine: from it all the solids are derived portant Huid of the and nourished, and all the other fluids are secreted; and animal it is hence the basis or common pabulum of every part. frame:

And as it is the source of general health so it is also of acted upon general disease. In inflammation it takes a considerable by external bodies, vo

share, and evinces a peculiar appearance. The miasms latile and of fevers and exanthems, are harmless to every other concrete.

part of the system, and only become mischievous when they reach the blood : and emetic tartar, when introduced into the jugular vein, will vomit in one or two minutes, although it might require, perhaps, half an hour if thrown into the stomach, and in fact does not vomit till it has reached the circulation. And the same is true

of opium, jalap, and most of the poisons, animal, mineWhen im- ral, and vegetable. If imperfectly elaborated, or with a perfect, the great source disproportion of some of its constituent principles to the of morbid rest, the whole system partakes of the evil, and a dyshabits.

thesis or morbid habit is the certain consequence; whence

• Trans. Medico-Chir. Soc. Vol. IX. p. 86.

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